Centrifuge rotors are typically used in laboratory centrifuges to hold samples during centrifugation. While centrifuge rotors may vary significantly in construction and in size, one common rotor structure is the fixed angle rotor having a solid rotor body with a plurality of cell hole cavities distributed radially within the rotor body and arranged symmetrically about an axis of rotation. Samples are placed in the cavities, allowing a plurality of samples to be subjected to centrifugation.
Conventional fixed angle centrifuge rotors may be made from metal or various other materials. However, a known improvement is to construct a centrifuge rotor by a compression molding and filament winding process wherein the rotor is fabricated from a suitable material such as composite carbon fiber. For example, a fixed angle centrifuge rotor may be compression molded from layers of resin-coated carbon fiber laminate material. Examples of composite centrifuge rotors are described in U.S. Pat. Nos. 4,738,656, 4,781,669, 4,790,808, 5,505,684, 5,601,522, 5,643,168, 5,759,592, 5,776,400, 5,833,908, 5,876,322, 6,056,910, and 6,296,798, and (owned by the assignee of the present disclosure), and the respective disclosures of which are expressly incorporated herein by reference in their entirety.
Because centrifuge rotors are commonly used in high rotation applications where the speed of the centrifuges may exceed hundreds or even thousands of rotations per minute, the centrifuge rotors must be able to withstand the stresses and strains experienced during the high speed rotation of the loaded rotor. During centrifugation, a rotor with samples loaded into the cavities experiences high forces along directions radially outwardly from the cavities and in directions along the longitudinal axes of the cavities, consistent with the centrifugal forces exerted on the sample containers. These forces cause significant stress and strain on the rotor body.
A centrifuge rotor should be able to withstand the forces associated with rapid centrifugation over the life of the rotor. A known approach to make centrifuge rotors that withstand such forces and related stresses includes making the rotor body a solid structure, with the cavities defined by bores or suitably sized depressions in the rotor that are configured to receive the samples therein. Rotors of this type, however, are relatively difficult and expensive to manufacture, and their rotational speeds may be limited due to the relatively high mass of the rotors. A need therefore exists for centrifuge rotors that provide improved performance in consideration of the dynamic loads experienced during centrifugation, and which address these and other problems associated with conventional rotors.